Gt911 Register Map -

The datasheet says, "Calculate the checksum of bytes 0x8047 to 0x80FD, then store the low byte at 0x80FE." Fine. But then you write 0x01 to 0x80FF... and the GT911 throws a tantrum if your checksum is wrong. It will simply ignore your config and revert to its internal "dumb" defaults. I spent two hours debugging why my X/Y axes were swapped until I realized I had a classic off-by-one in my checksum loop. The GT911 does not forgive. It does not forget.

Stores the X/Y coordinates and track IDs for up to 5 concurrent touch points. Commonly Used Registers (Command): : Read coordinates status. : Screen off (low power mode). : Enter Charge mode. (Buffer Status): gt911 register map